4512/1 practical
programming
AQA computer
science
Cand number:00000
Harry Strong
Harry strong
4512 Text Encryption
Wildern school
Design of solution
1. I have been asked to use a program which when we write a paragraph it
encrypts the content, encryption which is a type of cipher text. What is
encryption? Encryption is the best way to achieve data security. To read
an encrypted file, you must have access to a secret key or password that
enables you to decrypt it. Unencrypted data is called plain text; encrypted data
is referred to as cipher text.
2. What is Encryption? Is a text which is mixed up to try keep
3. Secret? My moving letters in and hour.
Task 1
Develop a main menu for the program. The options should be:



Encrypt message.
Decrypt message.
Exit the program.
Harry strong
4512 Text Encryption
Wildern school
Task 2
`Develop the part of the program that reads the contents of a text file to be encrypted.
When the user selects the ‘encrypt message’ option from the task menu created in
task 1 the program should:

Ask the user to enter the name of the file containing the message to be
encrypted.

Task 3
1. Generate a random number between 33126.
2. Convert the random number into its
equivalent ASCII character.
3. Repeat steps A and B eight times to
generate and eight character key.
4. Display the eight key to the user.
Harry strong
4512 Text Encryption
Wildern school
Task 4
1. Develop the part of the program that converts each character.
In the message into its ASCII code and encrypts it using the
flowy.
2. If the character is a space they do not encrypt the character.
3. Otherwise:

Convert the character into its ASCII code(eg B=66)
Task 5
1. Develop the part of the program that converts each character. In
the message into its ASCII code and encrypts it using the flowy.
2. If the character is a space they do not encrypt the character.
3. Otherwise:

Convert the character into its ASCII code(eg B=66)
Harry strong
4512 Text Encryption
Wildern school
Task 1 – During this task I create a main menu with three options
Prints main menu
Gives option for the user to enter 1,2,3 to
make the decision on what it is going to
do the three options there is are Encrypt
message, decrypt it or exit or exit
program depending on choice.
Task 2
Reads the file in the same folder
called sample.txt.
Harry strong
4512 Text Encryption
Wildern school
Task 3
Generates a random key and is eight
character’s long.
Task 4
Calculates an offset key for the user.
Technique used
Print()
choice
Input ()
If
else
For
import
ranndint
Int ()
While
Elif
Read
Chr()
Ord
Explanation
The print function in python is a function that outputs to your console window
whatever you say you want to print out.
This function on python gives you a choice of to two options which leads you
down a different path depending on choice.
Input what is put in, taken in, or operated on by any process or system.
A if statement is a programming conditional statement that, if proved true,
performs a function due to the put in information.
Else statement - executes some code if a condition is true and another code if
the condition is false.
Loop to play the program more than one time.
Is when something will be put into the program for example input and output.
Separate program and inserts random whole numbers.
This will make it a integer by making in to a whole number.
It is a loop which makes you choose one of an available option. The condition
may be any expression, and the true is any non-zero value. The loop iterates
while the condition is true. While choose <1.
The elif statement allows you to check multiple expressions for TRUE and
execute a block of code as soon as one of the conditions evaluates to TRUE.
It will read a file.
To identify the input is a character.
This will turn the character into a integer.
Harry strong
4512 Text Encryption
Wildern school
Test No Description
1
Test Date
Press option 1 If choice ==
on the main
1 print (“you
menu.
have chosen
to encrypt ”)
2
Please select Elif choice
2 on the main ==2 print
menu.
(you have a
choose to
encrypt)
3
Please select
3 on main
menu.
Elif choice
==print(“you
have chosen
to exit the
program”)
Expected
Actual
outcome
Outcome
This should
be printed on
screen if you
select ‘option
1’(“you have
chosen to
encrypt “)
This should
be printed on
screen if you
select ‘option
2(“you have
chosen to
decrypt”)
This should
be printed on
the screen as
(“exit the
program then
it will shut
down”)
Further
Action?
Harry strong
4512 Text Encryption
Wildern school
Testing and Evaluation
Harry strong
4512 Text Encryption
Wildern school
Task number
User need
Did I meet this How was this
need?
need met?
Task 1
Encrypt for
decrypt
message.
yes
Task 2
For the
yes
program to
read the file
and output the
file.
For the
yes
program to
create 8
random
generated
keys.
For the
yes
program to
output
Task 3
Task 4
How could this
need be better
met?
There was a
To go into the
menu that
encryption
displayed
option.
choice 1 or 2 to
encrypt/decrypt
message.
By a command
read file and
then a print the
file.
There was a
scale from 33 to
126
By using the
commands to
randomise the
character key.